如何检查数组中的任何字符串是否存在于另一个字符串中?
例如:
a = ['a', 'b', 'c']
s = "a123"
if a in s:
print("some of the strings found in s")
else:
print("no strings found in s")
我如何替换如果a在s:行得到适当的结果?
当前回答
data = "firstName and favoriteFood"
mandatory_fields = ['firstName', 'lastName', 'age']
# for each
for field in mandatory_fields:
if field not in data:
print("Error, missing req field {0}".format(field));
# still fine, multiple if statements
if ('firstName' not in data or
'lastName' not in data or
'age' not in data):
print("Error, missing a req field");
# not very readable, list comprehension
missing_fields = [x for x in mandatory_fields if x not in data]
if (len(missing_fields)>0):
print("Error, missing fields {0}".format(", ".join(missing_fields)));
其他回答
为了降低复杂度，jbernadas已经提到了aho - corasick -算法。
下面是在Python中使用它的一种方法:
从这里下载aho_corasick.py 将它放在与Python主文件相同的目录中，并将其命名为aho_corasick.py 用以下代码尝试该算法: 导入aho_corasick #(字符串，关键字) Print (aho_corasick(string， ["keyword1"， "keyword2"]))
注意，搜索是区分大小写的
python文档中推荐的regex模块支持这一点
words = {'he', 'or', 'low'}
p = regex.compile(r"\L<name>", name=words)
m = p.findall('helloworld')
print(m)
输出:
['he', 'low', 'or']
实现的一些细节:link
如果a或str中的字符串变长，您应该小心。简单的解决方案是O(S*(A^2))，其中S是str的长度，A是A中所有字符串长度的总和。要获得更快的解决方案，请查看用于字符串匹配的Aho-Corasick算法，该算法在线性时间O(S+A)内运行。
data = "firstName and favoriteFood"
mandatory_fields = ['firstName', 'lastName', 'age']
# for each
for field in mandatory_fields:
if field not in data:
print("Error, missing req field {0}".format(field));
# still fine, multiple if statements
if ('firstName' not in data or
'lastName' not in data or
'age' not in data):
print("Error, missing a req field");
# not very readable, list comprehension
missing_fields = [x for x in mandatory_fields if x not in data]
if (len(missing_fields)>0):
print("Error, missing fields {0}".format(", ".join(missing_fields)));
在另一个字符串列表中查找多个字符串的一种紧凑方法是使用set.intersection。这比大型集或列表中的列表理解执行得快得多。
>>> astring = ['abc','def','ghi','jkl','mno']
>>> bstring = ['def', 'jkl']
>>> a_set = set(astring) # convert list to set
>>> b_set = set(bstring)
>>> matches = a_set.intersection(b_set)
>>> matches
{'def', 'jkl'}
>>> list(matches) # if you want a list instead of a set
['def', 'jkl']
>>>
